My obligations to others, running through a good many years, are very great. With Professor E. E. Agger, I talked over very many of the problems here discussed, in the course of two years of close association at Columbia University, and gained very much from his suggestions and criticisms. Professor E. R. A. Seligman has read portions of the manuscript, and given valuable advice. Professor H. J. Davenport has given the first draft an exceedingly careful reading, and his criticisms have been especially helpful. Professor Jesse E. Pope supervised my investigations in the quantity theory of money in 1904-5, in his seminar at the University of Missouri, and gave me invaluable guidance in the general theory of money and credit then. More recently, his intimate first hand knowledge of European and American conditions, both in agricultural credit and in general banking, has been of great service to me. Mr. N. J. Silberling, of the Department of Economics at Harvard University, has been helpful in various ways, particularly by making certain statistical investigations, to which reference will be made in the text, at my request. Various bankers, brokers, and others closely in touch with the subjects here discussed have been more than generous in supplying needed information. Among these may be especially mentioned Mr. Byron W. Holt, of New York, Mr. Osmund Phillips, Editor of the _Annalist_ and Financial Editor of the _New York Times_, Messrs. L. H. Parkhurst and W. B. Donham, of the Old Colony Trust Company in Boston, various gentlemen in the offices of Charles Head & Co., and Pearmain and Brooks, in Boston, Mr. B. F. Smith, of the Cambridge Trust Company, Mr. W. H. Aborn, Coffee Broker, New York, Mr. Burton Thompson, Real Estate Broker, New York, Mr. Jas. H. Taylor, Treasurer of the New York Coffee Exchange, Mr. J. C. T. Merrill, Secretary of the Chicago Board of Trade, DeCoppet and Doremus, New York, and Mr. F. I. Kent, Vice President of the Bankers Trust Company, New York. My greatest obligations are to two colleagues at Harvard University. Professor F. W. Taussig has given the manuscript very careful consideration, from the standpoint of style as well as of doctrine, and has discussed many problems with me in detail. Professor O. M. W. Sprague has placed freely at my service his rich store of practical knowledge of virtually every phase of modern money and banking, and has read critically every page of the manuscript. None of these gentlemen, of course, is to be held responsible for my mistakes. I also make grateful acknowledgment of the aid and sympathy of my wife.